纳米磷酸铁锂的研究进展
摘要:橄榄石型LiFePO4作为新一代锂离子电池正极材料,具有比容量高、成本低、热稳定性好、环境友好等优点,拥有广阔的应用前景,但其低电导率的缺点使其商业化应用受到限制。通过合成纳米LiFeP04进而改善其电化学性能成为当前的研究热点之一。介绍了近年来国内外主要合成纳米LiFePO4的研究进展。分析了不同制备纳米LiFePO4方法的基本原理、前驱物、溶剂、重要工艺条件等。比较了不同工艺路线对LiFePO4结构和形貌的影响,探讨了合成纳米LiFePO4。所进行的研究工作。并指出了存在的问题。最后对纳米LiFePO4的产业化状况及发展趋势进行了展望。
关键词:纳米材料,磷酸铁锂,锂离子电池,正极材料,制备
Abstract:The olivine-type lithium iron phosphate was viewed as the most promising candidate cathode material of lithium ion batteries due to its advantages of high specific capacity, lower cost, good thermal stability and environment friendly. However, the lower electronic conductivity of LiFePO4 made it difficult to make full use of them in lithium ion batteries. The achievement of a nano-scale and homogenous particle size distribution of LiFePO4 for improving its electrochemical performance was one of the hot spots of research. In this paper, the progress in preparation of LiFePO4 material with different synthesis methods at home and abroad in recent years were summarized from such aspects as basic principle, reactive precursors, solvents, important technological conditions and so on. The impacts of these fabrication methods on the structure and performance of LiFePO4 powders pared, research work of synthesis of nano-scale LiFePO4 was explored and existing problems were pointed out. Finally, the industrialization and directions for future development of nano-scale LiFePO4 were prospected.
Key words:nano-material, lithium iron phosphate, lithium ion battery, cathode material, synthesis
纳米材料是指微观结构至少在一维方向上受纳米尺度调制的各种固态材料[1] ,其晶粒或颗粒尺寸在1~100nm数量级,主要由纳米晶粒和晶粒界面两部分组成,其晶粒中原子的长程有序排列和无序界面成分的组成后有大量的界面(6×1025m3/ 10 nm晶粒尺寸),晶界原子达15%~50%,且原子排列互不相同,界面周围的晶格原子结构互不相关,使得纳米材料成为介于晶态与非晶态之间的一种新的结构状态[2]。此外,由于纳米晶粒中的原子排列的非无限长程有序性,使得通常大晶体材料中表现出的连续能带分裂为接近分子轨道的能级。高浓度界面及原子能级的特殊结构,使其具有不同于常规材料和单个分子的性质如表面效应、体积效应、量子尺寸效应、宏观量子隧道效应等,导致了纳米材料的力学性能、磁性、介电性、超导性光学乃至力学性能发生改变,使之在电子学、光学、化工陶瓷、生物、医药等诸多方面具有重要价值,得到了广泛应用[3,4]。
由于能源问题和环境问题的日趋严重,并且传统的石化能源也会在未来使用殆尽,人们不得不去寻找新的替代能源。相应地人们的节能观念也逐渐增强,
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